In a letter released on Wednesday, members of leading law enforcement organizations are calling on the two presidential contenders to embrace the concept of criminal justice overhaul. But the message is aimed mostly at Donald J. Trump.

Hillary Clinton is already a strong supporter of making changes in sentencing and community programs to reduce the number of Americans in prison, and she reiterated that stance on Tuesday. Mr. Trump is campaigning on law and order and support for law enforcement. Police and prosecutor groups want to make sure that Mr. Trump realizes that support for them includes backing proposals for change, which they say will reduce crime as well as recidivism rates.

“Though this may seem counterintuitive, we know from our experience as law enforcement officials that over-relying on incarceration does not deter crime,” the groups said in the letter to Mr. Trump and Mrs. Clinton. “As prison budgets have continued to rise, funding for state and local law enforcement has been slashed, negatively impacting innovative work in the field including diversion programs, updating information-sharing systems, and smart policing tactics.”

With a bipartisan criminal justice package stalled in the Senate, the position of the next president on the issue is becoming even more critical to advocates of sentencing revisions.

“With finite prison space, we believe prison should be used for the most dangerous offenders,” the letter said.

It was signed by the Association of Prosecuting Attorneys, Law Enforcement Leaders to Reduce Crime and Incarceration, Major Cities Chiefs Association, the National District Attorneys Association and the Police Foundation. Organizers of the letter said the groups represent 30,000 current and former law enforcement professionals.